ProgramNode(0...6)(
  [],
  StatementsNode(0...6)(
    [CallNode(0...6)(
       nil,
       nil,
       (0...1),
       (1...2),
       ArgumentsNode(2...5)(
         [KeywordHashNode(2...5)(
            [AssocSplatNode(2...5)(IntegerNode(4...5)(), (2...4))]
          )]
       ),
       (5...6),
       nil,
       0,
       "a"
     )]
  )
)
